Hi...i am in Canada. After some searching on this site i am unable to find a similar post. We have prefabbed engineered floor joists/trusses up here in Canada. I am wondering how i go about using the deflecto calculator with this type of truss. The joists are nothing more than a 2x4 along the top and bottom with oriented strand board used in the center standing upright. I have no pic of one. Thanks

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advertguy2

11-12-2009, 01:49 PM

I'm in Canada as well, but I don't think that makes a difference. For pre-engineered joists you'll have to either call the manufacturer or look up their website to see if the info is there. I've called up the company that did my old house in the past and they've been very helpful. Hopefully you'll get the same help.

Regards,

Dan

bbcamp

11-12-2009, 02:01 PM

The Deflectolator doesn't even admit to the possible existance of engineered wood joists, such as yours. Such thoughts would fry it's tiny little whatnots.:D

You'll have to visit the manufacturer's website or call their tech support folks. Chances are, your floor will meet the L/360 criteria (may even meet L/480), but won't meet L/720 unless your house was designed with stone floors in mind.

roonie

11-12-2009, 06:36 PM

when these engineered joists first came available , i thought i kept hearing that these joists were far stronger than the solid wood joists. If that is in fact the case, should i just go ahead and insert the equivilent dimensions into the calculator? I think i know what you are going to say ......call the manufacture.

cx

11-12-2009, 09:14 PM

Welcome, Roonie. :)

You could enter something into the Deflectolator, and the Deflectolator will give you an answer, and then you'll know 'zackly what you know now.

Which, of course, is that you have engineered joists and there are no "equivilent dimensions" for you to enter into our calculator.

As Injineer Bob points out, your joist system was almost certainly designed to meet at least L/360 deflection standards, 'specially if the structure was built in a code compliance jurisdiction. If the spans are over about 14 feet, it's a very safe bet the joists were designed to L/480. And, again as Bob said, if no natural stone was specified on the original plans, it's very unlikely the joists were designed to L/720.